Reversible feed wheel mechanism for power strapping machines



Aug. 13, 1968 J. R. ANNIS, JR 3,396,889

REVERSIBLE FEED WHEEL MECHANISM FOR POWER STRAPPING MACHINES v Filed May23, 1966 2 Sheets-Sheet 1 INVENTOR= 7-, K M JAMES R. A/VN/S',JR. I00 A:0

By dwand. am

REVERSIBLE FEED WHEEL MECHANISM FOR POWER STRAPPING MACH INES Filed May23, 1966 Aug. 13, 1968 J. R. ANNIS, JR

2 Sheets-Sheet 2 m m mm mm w mm By: 5M (R United States Patent 3 396,889REVERSIBLE FEED WHEEL MECHANISM FOR POWER STRAPPING MACHINES James R.Annis, Jr., Northbrook, Ill., assignor to Signode Corporation, Chicago,11]., a corporation of Delaware Filed May 23, 1966, Ser. No. 551,975 9Claims. (Cl. 226143) The improved reversible feed wheel mechanismcomprising the present invention has been designed primarily for use inconnection with stationary power strapping machines of the fullyautomatic type wherein plastic or steel strapping is fed or payed out inone direction through a chute which encircles the package or bundleundergoing strapping and then, after the strapping has been caused tocompletely encircle the package, its direction of feed is reversed totension the strapping about the package. The invention is however notlimited to such use and feed wheel mechanisms embodying the principlesof the invention may, if desired, with or without modification asrequired, be employed in connection with any power strapping machine,whether fully automatic or semiautomatic, where the requirements arethat a feed wheel, at the commencement of the machine cycle, impel thestrapping in one direction for strap-feeding purposes and then, at asubsequent point in the machine cycle, reverse its direction of rotationto tension the previously fed strapping. Irrespective however of theparticular use to which the invention may be put, the essential featuresthereof remain substantially the same.

It has long been the practice, in connection with strapping tools, bothportable and stationary alike, to support the strap-tensioning feed ortraction wheel at the distal end of a swinging support which is sopivoted to the tool framework that the feed wheel approaches thereaction anvil or back-up wheel at a relatively small approach angle,thus causing a binding or wedging action on the strapping which is afunction of the cotangent of the angle involved. Thus, the greater thetension in the strapping, the greater will be the binding action on thestrapping, this phenomenon being commonly referred to as aself-energizing action.

Where a feed wheel is obliged to impel the. strapping in a directioncounter to the direction of tensioning for the purpose of feeding thestrapping into a chute toward or around the work, for example into achute which encircles the strapping area, reaction forces on the feedwheel are such that a rapid self-deenergization of the feed wheel takesplace as the approach angle becomes greater and, as a result of theconsequent loss of pressure upon the strapping, there is a tendency forslippage of the feed wheel upon the strapping with consequent abrasionof the latter due to a milling action so that the interstices betweenthe driving teeth or protuberances on the feed wheel become filled withparticles. Thereafter, where resistance to strapping feed is encounteredin advance of the feed wheel, as for example where the strapping isbeing forced forwardly through a strap chute, the tractional efficiencyof the feed wheel is impaired.

With the advent of relatively high speed strap feeding operations,amounting in some cases to as much as six feet per second, such abrasionof the strapping is augmented by the tendency of the shock load which isapplied to the strapping when the slack in the strapping is initiallytaken up and the inertia load of the rotary strapping reel in thestrapping dispenser is encountered. At this moment, and until thedispenser gets up to normal feeding speed, deep mill cuts and otherimpressions are imparted to the strapping by the feed wheel, therebyweakening the strapping.

'These problems of strapping feed have long plagued 3,396,889 PatentedAug. 13, 1968 the designers of feed wheel mechanisms and various meanshave been devised in an etiort to minimize the amount ofself-deenergization which takes place when a strap-tensioning feed wheelis rotated counter to the direction of strap tensioning for strapfeeding purposes. The most obvious of these means has been to increasethe spring pressure normally applied to the swinging feed wheel support,but this has resulted in a more pronounced feed wheel marking upon thestrapping and other damage to the strapping finish, as well as causingincreased strapping curl and feed wheel camber due to offset lateralsupport for the feed wheel shaft. Such considerations are particularlypronounced where plastic or other nonmetallic strapping is concerned.

The present invention is designed to overcome the above-notedlimitations that are attendant upon the construction and operation ofreversible feed wheel mechanisms which operate upon the strapping in onedirection for strapping feed purposes and in the other direction forstrap tensioning purposes and, toward this end, the inventioncontemplates the provision of a novel feed wheel mechanism in which aself-energizing action takes place in both directions of rotation of thefeed wheel.

The provision of such a feed wheel mechanism constitutes the principalobject of the invention and in the accompanying two sheets of drawingsforming a part of this specification, several embodiments of theinvention by means of which such dual feed wheel energization may beaccomplished have been illustrated. Other ancillary objects andadvantages of the invention, will readily suggest themselves as thenature of the invention is better understood.

In these drawings:

FIG. 1 is a sectional view taken substantially vertical- 1y, centrallyand longitudinally through a reversible feed wheel mechanism embodyingthe principles of the present invention the mechanism embodying a novelfeed wheel anvil and gripper member and being shown as operativelyassociated with the related parts of a power strapping machine;

FIG. 2 is a sectional view taken substantially on the line 2-2 of FIG. 1in the direction of the arrows;

FIG. 3 is a sectional view taken substantially on the line 3-3 of FIG. 1in the direction of the arrows;

FIG. 4 is a side elevational view, partly in section and entirelyschematic in its representation, illustrating the mode of operation ofthe structure shown in FIG. 1;

FIG. 5 is a schematic view, similar to FIG. 4 illustrating the structureand mode of operation of a modified form of reversible feed wheelmechanism embodying the present invention;

FIG. 6 is a schematic view similar to FIGS. 4 and 5 showing anothermodified form of feed wheel mechanism embodying the present invention;and

FIG. 7 is a schematic view similar to FIGS. 4, 5 and 6, showing theanvil member of FIG. 4 devoid of its gripper function.

Referring now to the drawings in detail and in particular to FIGS. 1 to3 inclusive, one form of reversible feed wheel mechanism incorporatingthe principles of the present invention has been designated in itsentirety at 10 and it is shown for exemplary purposes as being embodiedin a fully automatic power strapping machine of the type which operatesto feed a length of strapping material in one direction about a bundleso that its free end is positioned in overlapping relationship withrespect to the standing portion thereof which leads to a source ofstrapping such as a coil of strapping, after which the free end of thestrapping is fixedly clamped and the direction of movement of thestrapping is reversed to tension the strapping and shrink the same onthe bundle. When the required degree of tension has been attained, themachine operates to position and crimp'a seal about the overlappingportion of the strapping or otherwise unite these overlapping portionsand, finally. it operates to sever the standing portion of the strappingto free the strapped bundle.

The feed wheel mechanism is, with suitable modification as required,applicable to a wide variety of automatic power strapping machines butfor exemplary, purposes it has been shown as being incorporated in astrapping machine of the general type, shown and described in UnitedStates patent to Crosby et al., No. 2,915,003,

granted on Dec. 1, 1959, and entitled Power Strapping Machine, only suchparts of the machine as have ;a direct work and which is comprised ofparallel longitudinally extending side walls 14 and 16 and a-rear wall18, the front end of the housing being open. The machine is so designedthat the area or region immediately below the housing 12 constitutes astrapping station ST where'an article such as the article shown at A ismoved into position beneath the housing for strappingjpurposes. The

strapping station ST is defined by a strap guiding chute 20 whichencircles the article A and provides a substan-' tially closed path forthe strapping. Strapping S is drawn from a suitable strapping dispenser(not shownland is fed by the mechanism 10 through the housing 12forwardly into the receivingend 22 of the chute 20, from whence it isprojected in a closed path substantially completely around the article Aso that it emerges from the discharge end 24 of the chute and thentraverses a short distance beneath the housing 12 through a guidechannel 26 until the leading end region 28 thereof overlaps andunderlies the standing portion 30 of the strapping which exists at asealing station SS. At this time, the mechanism 10 becomes effective toclamp the free end region of the strapping and reverse the direction ofmovement of the standing portion of the strapping through the housing 12whereupon the article-encircling portion of the strapping S will bedrawn in centripetal fashion from the chute 20 to shrink the same aboutthe article, after which continued reverse movement of the strappingwill tension the thus shrunk strapping. When the required orpredetermined degree of tension has ben attained in the encircling loopof strapping, a previously applied seal 32 is crimped in position aboutthe overlapping portions .of the strapping at the sealing station SS andthe free end region of the strapping is severed from the encircling loopto release the entrapped article from the source of strapping, suitablecrimping jaw instrumentalities 34 and shearing instrumentalities 36being provided at the sealing station for this purpose.

The general arrangement of parts thus far described, with the exceptionof the specific construction of the feed wheel mechanism 10, isconventional since reversible feed wheel mechanisms are currently in usefor initially feeding strapping material in one direction to force thesame through an article-encircling chute and for thereafter feeding thestrapping in the opposite direction to shrink and tension the strappingabout an article. Thus, no claim is made herein to any novelty inconnection with the strapping machine operations thus far described, thenovelty of the present invention residing rather in the details of thefeed wheel mechanism per se by means of which a firm gripping action isattained upon the strapping by the feed wheel proper which is associatedwith the mechanism, regardless of whether the strapping is undergoingforward strapping feed into the chute 20 or reverse strapping feed forstrap tensioning purposes.

Considering nowthe feed wheel mechanism 10 in greater detail, thismechanism involvesin its general organization a toothed or serrated feedwheel proper which is carried at the lower end of a bifurcated link 52,the upper end of which is pivoted to a cross pin 54 which extends acrossthe housing 12 between the two walls 14 and 16. The feed wheel 50 issecured to the drive shaft 55 of a reversible motor M and is straddledby the furcations of the link 52 as best seen in FIG. 2. The motor M isprovided with a housing 56 having a hub portion 57 secured in an opening58 formed in one of the furcations of the link 52, the hub portionpassing through a clearance opening 60 formed in the side wall 16 of thehousing12. The motor is thus supported by the link 52 near the distal orlower end thereof so that it moves bodily with the link throughout thelimited swinging movements of the latter about the axis of the pivot pin54. i

, The feed wheel 50 cooperates with a combined gripper and anvil member62 in the form of a rocker element to feed the strapping S which isinterposed between these two elements either in a forward direction toproject the strapping into and through the chute 20 for articleencircling purposes, or in a. reverse or rearward direction to shrinkthe strapping loop and tension the same about the article as previouslydescribed. This rocker element 62 is generally in the form of apentahedron which is substantially of triangular configuration inlongitudinal elevation as shown in FIG. 1. Stated otherwise the rockerelement 62 is wedge-shape in its design. The element 62 is possesssed ofthree functional sides including a base side 64, a. rear side 66 whichextends at a right angle to the baseside, and a working side 68 whichconstitutes the hypotenuse ofthe triangle. The rocker element 62 ispivoted for limited swinging movement about a horizontal axis by meansof a pin 70 which projects between the side wallsj14 and 16 and servesto pivotally support the rocker element in the vicinity of the juncturebetween the sides 64 and 66 for free swinging movement in eitherdirection.

The working side 68 of the rocker element 62 is formed with a shallow'semicylindrical depression or well 72 therein having a radius ofcurvature which is preferably slightly greater than the radius of thefeed wheel 50 and into which depression the periphery of the feed Wheelprojects. When the feed wheel is centered within the depressi0n'72 asshown in FIG. 1, i.e., when the axis of the link 52 is such that itintersects the transverse axisof the pivot pin 70, the periphery of thefeed Wheel lies close to the bottom of the depression 72 but isseparated therefrom by'a distance slightly less than the thickness ofthe strapping S. Such a position has been illustrated in FIG. 1 but itis an unnatural one and represents a mid-position of the link 52 andfeed wheel 50 and only occurs during the machine cycle when thedirection of rotation of the feed wheel is undergoing reversal. In thenormal position of the parts, as well as during strap tensioningoperations, the feed wheel effectively bears against the forward region72a of the depression, either under the influence of gravitationalforces acting on the motor M, or a self-energizing action in onedirection as will be described presently, or both. During strap feedingoperations into the chute 20, the feed Wheel effectively bears againstthe rear regions 72b of the depression due to a similar self-energizingaction in the opposite direction.

The strapping is initially passed through the housing by projecting thefree end thereof forwardly through an opening provided in the rear Wall12 and across the upper surface of the side 68 and from thence into thereceiving end 22 of the chute 20, the strapping being guided by the feedwheel 50 which at the time is caused to rotate in a clockwise direction,so that it follows the contour of the depression 72. The strapping afterbeing initially thus introduced through the housing, remains in thehousing until the supply of strapping leading from the dispenser isexhausted. In order to guide the strapping through the housing andprevent it from clinging to the feed wheel 50, a pair of substantiallyidentical guide blocks 82 are nested within channel-like depressions. 84(FIG. 3) which are established by reason of pairs of upstanding flanges86 on the upper side 68 of the rocker element 62 and are secured inposition between the respective pairs of flanges by anchoring pins 88.The underneath faces of the blocks 82 are spaced slightly above theupper side 68 to afford a clearance for the strapping.

The width of the blocks 82 is substantially equal to the width of thestrapping S and the width of the feed wheel 50 is less than the width ofthe strapping. A pair of spaced apart flanges 90 on each of the guideblocks 82 straddle the peripheral region of the feed wheel but liewithin the marginal confines of the strapping so that these latterflanges act as stripper elements to constrain the strapping to followthe contour of the upper working surface 68 of the rocker element 62rather than cling to the feed wheel and thus cause jamming of themechanism.

The previously mentioned crimping jaw instrumentalities 34 and shearinginstrumentalities 36 at the sealing station SS my be of any conventionalconstruction but, for examplary purposes herein they are illustrated asbeing of the type shown and described in United States patent to Meier,No. 3,150,694, granted on Sept. 29, 1964, and entitled Strapping Tool.Reference may be had to such patent for a full understanding of theseinstrumentalities 34 and 36 but, for descriptive purposes herein it isdeemed sufficient to state that the crimping jaw instru-mentalitiesinclude a pair of cooperating crimping jaws 92 which operate at anappropriate point in the machine cycle to loosely maintain a seal suchas the seal 32 around the overlapping portions 28 and 30 of thestrapping S and hold the same thus loosely positioned during the straptensioning operation and then, after such tensioning operation has beencompleted, to crimp the seal. The shearing instr-umentalities 36 includea depressible plunger 94 which, upon depression thereof, engages theseal 32 and forces the same downwardly so as to shear the standingportion of the strapping against a fixed shear block 96.

As previously stated, when the free end region of the strapping Semerges from the discharge end 24 of the chute 20 it traverses the guidechannel 26 and is thereby conducted to the shearing station SS where itassumes its underlying position with respect to the standing portion 30.This guide channel 26 is established by means of a swinging gate member100 which is pivoted by a pin 102 to one side of the rocker element 62and has a foot portion 104 which normally underlies the latter element.The gate member 100 is biased to its normal position by a torsion spring106 surrounding the pivot pin 102. During the shrinking of the loop ofstrapping S about the article undergoing strapping, this gate member 100is deflected by the inward centripetal movement of the strapping so thatthe gate member offers no resistance to removal of the strapped articlefrom the strapping zone.

An anvil foot 110 also normally underlies the forward end region of therocker element 62 'and constitutes a part of a second swinging gatemember 112 of C-shape design. The gate member 112 is pivoted by a pin114 (FIG. 2) to an overhead support 115 constituting a part of themachine framework and which is disposed well above the level of the link52. The anvil foot 110 may be formed with serrations on its upper sidethus establishing a movable gripper jaw 116 which is designed forcooperation with similar serrations which establish a fixed gripper jaw118 on the underneath side of the extreme forward region of the rockerelement 62 in clamping the strapping therebetween immediately prior tothe strap tensioning operation. The gate member 112 is capable of beinglaterally displaced as shown in dotted lines in FIG. 2 after the strapsevering operation so as to release the tensioned loop of strappingwhich surrounds the article and thus release the article so that it maybe withdrawn from the strapping zone.

The operation of the feed wheel mechanism may readily be described byreference to the schematic illustration of FIG. 4 wherein the principalcomponents thereof have been, to a large extent isolated from theimmediate strapping machine environment and wherein the guide' blocks 82have been removed in the interests of clarity. Reference to FIG. 4 willreveal the fact that during that portion of the machine cycle when thestrapping S is undergoing feeding in a forward direction, i.e., to theleft as seen in this view, the feed wheel will rotate in a clockwisedirection to thus impel the strapping which overlies the depression 72.Since the combined effective length of the swinging link 52 and thediameter of its supported feed wheel is such that in the mid-position ofthe link 52 the strapping will be lightly confined between the feedwheel 50 and the bottom of the depression 72, the tendency for the feedwheel during such clockwise rotation will be to tractionally engage thestrapping and, by a locomotive action, travel generally rearwardly so asto cause the link 52 to swing in a counterclockwise direction. Thepressureexerted upon the portion 72b of the depression 72 will cause therocker element 62 to swing in a clockwise direction, thus elevating theserrated gripper jaw 116 from the fixed gripper jaw 118 to allow theforward end region of the strapping to pass between these two jaws afterthe strapping has traversed the arcuate extent of the chute 20 andpassed forwardly through the guide channel 26. At the same time theupper edge. region of the rear side 66 of the rocker element 62 willengage the wall 18 of the housing 12 to limit the extent of clockwiseswinging movement of the rocker element 62 and, thereafter, a wedgingaction of the link 52 and feed wheel 50 will take place wherein the link52 is placed under relatively high compression between the fixed pivotpin 54 and the portion 72b of the depression 72, this wedging actionbeing commonly referred to in the art of feed wheel suspension devicesas a self-energizing action. In the present instance, the magnitude ofthe self-energizing action is a function of the cotangent of the angleinvolved between the axis of the link 52 and a plane which is tangent tothe increment of linear contact between the feed wheel 50 and surfaceportion 72b at any given instant during the strap feeding operation.

During such portion of the machine cycle when the feed wheel is rotatingin a counterclockwise direction so as to initially pull the strapping incentripetal fashion from the chute 20 and shrink the loop about thearticle A, and to thereafter tension the strapping about the article aspreviously described, a similar self-energizing action of the feed wheeland its supporting link will take place by reason of the locomotiveaction of the feed wheel on the strapping S tending to rock thesupporting link 52 in a clockwise direction. The pressure of the feedwheel upon the surface portion 72a of the depression 72 will rock thegripper element 62 in a counterclockwise direction, thus forcing themovable gripper jaw 116 into effective clamping cooperation with thefixed gripper jaw 118 to clamp the free end portion of the strappingtherebetween.

From the above description it will be apparent that the present feedwheel mechanism 10 is effective to establish a self-energizing operationof the feed wheel against the strapping S during impelling of the latterin either direction. The energizing angles involved during rotation ofthe feed wheel in either direction may be regulated to accommodate thedesired degree of pressure upon the strapping by proper selection of thepivotal axis of the pin to vary the normal clearances between the rockerelement 62 and the two abutment surfaces which limit the swingingmovements of this element. In the illustrated form of the invention,during feeding of the strapping S in a direction to project the sameforwardly into the entrance end 22 of the chute 20, the energizing angleinvolved need not be steep since the frictional resistance offered tothe strapping passing through the chute is not great, even when a fullcomplement of strapping is disposed within the chute near the end of thestrap feeding portion of the machine cycle. During initial strap feedingoperations and before all of the slack existing in the portion of thestrapping leading from the feed wheel mechanism to the rotary reel typedispenser has been taken up, relatively light pressure upon thestrapping by the feed wheel will suffice to impel the strap forwardly.At such time as this slack has been fully taken up and the shock loadincident to the inertia of the strapping reel is encountered, theconsequent drag upon the power driven feed wheel will increase theenergizing angle and maintain such an increase until such time as thestrapping reel gathers full dispensing speed of rotation. Thereafter thefrictional drag upon the feed wheel will decrease and normal feedingoperations under light strapping pressure will obtain. In this mannerlong stretches of feed wheel impression or other markings on the surfaceof the strapping will the avoided.

During reverse rotation of the feed wheel 50 for strap tensioningpurposes, adequate pressure upon the strapping will at all times beeffective to perform the tensioning operation. As the tension in thestrapping increases progressively, the binding action of the feed wheelon the strapping will increase commensurately because of the increase inthe steepness of the energizing angle. The resultant increase ofpressure on the strapping will be translated to the movable gripper jaw116 through the rocker element 62 so that there will be no danger ofslippage of the free end region of the strapping from between thesejaws.

In FIG. a modified form of reversible feed wheel mechanism has beenillustrated schematically and designated in its entirety at 210. In thisform of the invention, the same general principle of dual-energizationof the feed wheel 250 and its supporting links 252a and 252b obtains asin the case of the feed wheel 50 and its single supporting link 52. Dueto the similarity of parts involved, and in order to avoid needlessrepetition of description, similar characters of reference but of ahigher order have been applied to the corresponding parts as between thedisclosures of FIGS. 4 and 5.

In the feed wheel mechanism 210, the motor shaft 256 which supports thefeed wheel 250 is suspended from the lower ends of the two supportinglinks 252a and 252b. These links are of equal length and they in turn,are loosely and pivotally supported adjacent their upper ends on fixedpins 254 which are spaced from each other and lie in the same horizontalplane. The spacing of the pins 254 and the length of the links 252a and25212 are such that the links are disposed substantially at a rightangle to each other with the inclination thereof being on the order of45. The pivotal support for the links 252a and 252b is established bymeans of longitudinally extending slots 253 through which the pins 254extend.

The feed wheel 250 cooperates with a fixed back-up anvil block 310against which it effectively bears to impel the strapping S either in aforward direction or in a reverse direction, depending upon thedirection in which the feed wheel supporting motor shaft 256 is rotated.It will be understood that the gravitational force .of the motor M2 asapplied to the feed wheel through the shaft 256 may be relied upon toestablish the necessary initial pressure be tween the feed wheel and thestrapping S for strap-impelling purposes. However, if desired, each ofthe links 252:: and 252b may be yieldingly biased in opposite directionsrespectively by springs 257 to attain this initial feed wheel pressureon the strapping. This spring biasing of the links 252a and 252b may beemployed in an installation where the overlapping portions of thestrapping extend vertically along a vertical side of the articleundergoing strapping so that the gravitational force of the motor is notavailable for pressure application.

It is to be noted that when the feed wheel is rotating in a clockwisestrapfeeding direction, self-energization of the feed wheel against thestrapping will take place by reason of the tendency for the link 2521;to swing in a counterclockwise direction and thus cause the lower endregion of the associated slot 253 to engage the adjacent pin 254 andplace the link 2521) under compression. At the same time the link 252awill follow the locomotive or tractional movement of the feed wheel 250and the link 252a will ride free on the associated pin 254. Conversely,when the feed wheel is rotating in a counterclockwise strap tensioningdirection, self-energization of the feed wheel on the strapping willtake place by reason of the tendency for the link 252a to swing in aclockwise direction and effect engagernent of the lower end region ofthe associated slot with the adjacent pin 254 and thus place the link252a under compression in a manner similar to that previously describedin connection with the link 252b during strap feeding operations.

In FIG. 6 a further modified form of reversible feed wheel mechanism hasbeen schematically illustrated and designated at 410. Again, due to thesimilarity of the mechanism 410 with the mechanisms 10 and 210', and inorder to avoid needless repetition of description, similar referencecharacters of a still higher order have been applied to thecorresponding parts as between the structures of FIGS. 5 and 6.

In the form of the invention shown in FIG. 6, the two links 252a and252b have been replaced by a single generally triangular supportingplate 452 which, in effect, constitutes a supporting link for the feedwheel 450. The feed wheel supporting motor shaft 456 is pivotallysupported near the lower corner of the triangular plate 452 while theplate itself is fioatingly supported on pins 454 which project througharcuate slots 453 adjacent the two upper corners of the triangle. Thefeed wheel 450 cooperates with a freely rotatable back-up wheel 510 forstrap gripping purposes. The effect is similar to that which would beattained if the two links 252a and 252b were to be fixedly secured toeach other so as to constitute in effect a bell crank arrangement.Self-energization of the feed wheel 450 against the back-up wheel 510 isattained regardless of the direction of rotation of the feed wheelinasmuch as the shortest distance between the axis of the feed wheeldrive shaft 456 and the axis of either of the two pivot pins 454, aswell as the radius of the feed wheel 450, are such that at no time maythe feed wheel swing free of the backup wheel 510, regardless of thedirection of tilting movement of the triangular supporting link or plate452. If desired, the plate' 452 may be biased by a single compressionspring 457 similar in function to the springs 257 associated with thelinks 252a and 252b of FIG. 5.

In the form of feed wheel mechanism 610 shown in FIG. 7, the feed wheelmounting including the feed wheel 650, its supporting link 652, and thepivot pin 654 for the link, remains substantially the same as the feedwheel mounting of the feed wheel mechanism 10 of FIG. 4. The anvilmember 610 is similar in its construction to the anvil member or rockerelement 62 but, instead of being movable, it is fixed relative to thestrapping machine framework and thus is devoid of any associated grippermeans for the free end region .of the strapping S. Utilizing similarreference numerals of a still higher order to designate thecorresponding parts as between the disclosures of FIGS. 4 and 7, theanvil member 610 is formed with a semi-cylindrical depression 672 havingreaction surfaces 672a and 672b which cooperate with the strapping S andfeed wheel 650 during strap feeding and strap tensioning operationsrespectively in precisely the same manner as described in connectionwith the feed wheel mechanism 10.

It will be understood that in the forms of the invention shown in FIGS.4, 5, 6 and 7, the various pivot pins 54, 254, 454 and 654 constitutefixed elements on the strapping machine framework and that the feedwheel reaction members, i.e., the rocker element 62, the anvil blocks510, 610 and the back-up wheel 510 have fixed supports therefor on theframework, although the members may, if desired, be capable ofdisplacement for strap clearance purposes after the strapping operationhas been completed as is the case in connection with the anvil member orfoot 210 of FIGS. 1 and 3. Unlike the movable reaction rocker element ofFIG. 4, these latter reaction elements are devoid of any gripperfunction, it being understood that separate gripper means for thestrapping will be provided in the vicinity of the strapping station.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit of the invention. Therefore, onlyinsofar as the invention has particularly been pointed out in theaccompanying claims is the same to be limited.

Having thus described the invention, what I claim and desire to secureby Letters Patent is:

1. In a strapping machine having a framework, a reversible feed wheelmechanism for feeding a length of strapping in one direction forarticle-encircling purposes and in a reverse direction forstrap-tensioning purposes, said mechanism comprising: a reaction membersupported by the framework, a rotatable feed wheel designed forcooperation with said reaction member for tractionally feeding strappingthereacross in opposite direction, and a suspension linkage movablysupporting said feed wheel on the framework and including a link portionwhich is effective under compression and through the strapping to causeprogressive binding of the feed wheel against the reaction member underthe influence of the locomotive action of the feed wheel on thestrapping during rotation of the feed wheel in either direction, andmeans for selectively rotating the feed wheel in opposite directions.

2. In a strapping machine, a reversible feed wheel mechanism as setforth in claim 1, wherein the link portion which is effective undercompression during rotation of the feed wheel in one direction, and thelink portion which is effective under compression during rotation of thefeed wheel in the other direction, are embodied in a single link theupper end of which is pivoted to the framework and the lower end ofwhich rotatably supports the feed wheel.

3. In a strapping machine, a reversible feed wheel mechanism as setforth in claim 1, wherein said link portion of the suspension linkagehas its proximate end pivoted to the framework, said feed wheel beingpivotally mounted on the distal end of said link portion.

4. In a strapping machine, a reversible feed wheel mechanism as setforth in claim 1, wherein the link portion which is effective undercompression and through the strapping during rotation of the feed wheelin one direction has its proximate end loosely pivoted to the framework,and wherein the link portion which is effective under compression andthrough the strapping during rotation of the feed wheel in the otherdirection likewise has its proximate end loosely pivoted to theframework, the regions of pivotal connection for said link portionsbeing spaced from each other.

5. In a strapping machine, a reversible feed wheel mechanism as setforth in claim 4, wherein said link portions are embodied in a commonrigid link member.

6. In a strapping machine having a framework, a reversible feed wheelmechanism for feeding a length of strapping in one direction forarticle-encircling .purposes and in a reverse direction forstrap-tensioning purposes, said mechanism comprising: a feed wheelsupporting link having its proximate end pivoted to the framework forswinging movement of the link in opposite directions, a strap-impellingfeed wheel rotatably mounted on the distal end of said link, reactionmeans supported by the framework and between which means and the feedwheel the strapping passes during impelling thereof in either direction,said reaction means presenting a pair of reaction surfaces against whichthe feed wheel is adapted to effectively bear through the strapping andwhich are so disposed with respect to the arcuate path of swingingmovement of the feed wheel that the locomotive action of the feed wheelon the strapping urges the feed wheel bodily toward one of said surfacesto increase the pressure of the feed wheel on the strapping when thefeed wheel is rotated in one direction, and urges the feed wheel bodilytoward the other surface to increase the pressure of the feed wheel onthe strapping when the feed wheel is rotated in the other direction, andmeans for selectively rotating said feed wheel in opposite directions.

7. In a strapping machine, a reversible feed wheel mechanism as setforth in claim 6, wherein said reaction means comprises a reaction blockhaving a shallow depression therein into which the peripheral region ofthe feed wheel projects, the opposite side surfaces of said depressionestablishing said pair of reaction surfaces.

8. In a strapping machine, a reversible feed wheel mechanism as setforth in claim 7, wherein said depression is of arcuate configurationand on a radius of curvature greater than the combined effective radialextent of the link and its supported feed wheel.

9. In a. strapping machine, a reversible feed wheel mechanism as setforth in claim 7, wherein said reaction block is in the form of a rockerelement pivoted to the framework for limited rocking movement inopposite directions and about an axis which is intersected by thelongitudinal axis of the link when the feed wheel is in an intermediateposition out of effective engagement with either reaction surface, andan abutment positioned in the path of rocking movement of the rockerelement in each direction for limiting the extent of such rockingmovement, one of said abutments, in combination with the adjacentopposing portion of the gripper element, constituting a gripper foot forthe free end of the length of strapping.

References Cited UNITED STATES PATENTS 3,118,584 1/1964 Brouse 226143ALLEN N. KNOWLES, Primary Examiner.

J. P. MULLINS, Assistant Examiner.

1. IN A STRAPPING MACHINE HAVING A FRAMEWORK, A REVERSIBLE FEED WHEELMECHANISM FOR FEEDING A LENGTH OF STRAPPING IN ONE DIRECTION FORARTICLE-ENCIRCLING PURPOSES AND IN A REVERSE DIRECTION FORSTRAP-TENSIONING PURPOSES, SAID MECHANISM COMPRISING: A REACTION MEMBERSUPPORTED BY THE FRAMEWORK, A ROTATABLE FEED WHEEL DESIGNED FORCOOPERATION WITH SAID REACTION MEMBER FOR TRACTIONALLY FEEDING STRAPPINGTHEREACROSS IN OPPOSITE DIRECTION, AND A SUSPENSION LINKAGE MOVABLYSUPPORTING SAID FEED WHEEL